Apparatus for controlling tension in a web



Dec. 20, 1960 L. RocKsTRoM APPARATUS FOR CONTROLLING TENSION IN A WEB Filed Dec. 18, 195'? Z50/VA@ /PdcKy/fw United States Patent APPARATUS FOR CONTROLLING TENSION IN A WEB Leonard Rockstrom, Madison, N J., assignor to Cameron Machine Company, Brooklyn, N.Y., a corporation of New York Filed Dec. 18, 1957, Ser. No. 703,630

'14 Claims. (Cl. 242--75.43)

This invention relates to improved apparatus by means of which it is possible not only to control very accurately the tension in a web during running of the latter from one roll to another but, also, to control tension in the web upon stopping of the movement of the web from one roll to another to avoid either too high a tension, which might cause breakage of the web, or too low a tension, which might cause the web to pay out uncontrollably from the payout roll. Such winding of a web is usually done in conjunction with some processing of the web.

In such apparatus, commonly referred to as winders or winding machines, power is ordinarily applied to a take-up roll and a desired tension is maintained in the web by imposing a suitable braking effect upon a pay-out roll. It is common practice to arrange for the web, in passing from the pay-out roll to the take-up roll, to pass over a floating roll, sometimes called a dancer roll, which is so mounted that variations in the tension of the web cause displacement of the dancer rolls axis; and such displacement being utilized to control a brake which is effective upon the pay-out roll to maintain a substantially constant tension in the web. Such dancer-roll arrangements have been used with some success in achieving compensation for fluctuations in web tension, although such compensatory action sometimes has not been as rapid as could be desired because of the fact that heretofore such dancer rolls have been adapted to function with respect to only a single brake control.

It has also been common practice in the past to provide a follower which is maintained in constant engagement with the outer surface of the pay-out roll and functions, as the diameter of the latter decreases, to effect a gradual variation or adjustment of means for controlling a brake which is operative upon a pay-out roll to initiate and maintain a suitable tension upon the web passing from said roll.

An important object of the present invention is the provision of a brake-control arrangement which is governed by the movement of a floating or dancer roll and serves to yield a more satisfactory response in the braking means associated with the pay-out roll to more rapidly and effectively achieve compensation for tension fluctuations in the running web.

Another important object of this invention is the provision of a braking arrangement for a pay-out roll wherein a single brakeoperating element is acted upon both by means which are controlled by such a dancer roll and by means which are controlled by such a follower.

Another important object of this invention is the provision of a brake-control arrangement for a pay-out roll, which arrangement, throughout the running of a Vweb from the pay-out roll to a take-up roll, is constantly maintained in condition to react upon stopping of the winding machine in substantially direct proportion to the weight or inertia in any remaining portion of the pay-out roll so that the web extending between the two ice rolls will be maintained at such tension that it will neither break from excessive tension nor unwind uncontrollably from the pay-out roll as a result of a dearth of tension.

According to the feature of this invention which relates more particularly to the provision of rapid response to the movements of the dancer roll to achieve rapid compensation in the tension of the running web, this invention comprehends the use of separate cams moved in unison by the movement of the dancer roll, the two said cams acting oppositely upon means for actuating an operating element for operating a brake on the pay-out roll. The mentioned opposite action is such as to impose a force functioning in one direction upon said brake-operating element and, at the same time, to release or reduce a force acting in an opposite direction on the same brake-operating element. This opposite action achieves great rapidity in the operation of the brake and, consequently, yields very rapid compensation for variations in the tension of the running web.

According to another feature of this invention, two distinct cams or cam surfaces are arranged to be moved in unison by a follower which engages the exterior of the pay-out roll and moves said cams gradually as the diameter of the pay-out roll decreases. One of these cams, which may be referred to as a diameter compensation cam, operates to diminish the braking effect gradually upon a pay-out roll as the diameter of the latter decreases. The other of these two cams, which may be referred to as an inertia cam, shifts, of course, as the follower moves with the gradual reduction in the diameter of the pay-out roll, but said other cam does not become effective until the winding :machine is being stopped because the control means with which said other cam is associated are normally inactive and are arranged to become active only when the motive power applied to the take-up roll is terminated to stop the machine. At such a time, the controls for stopping the machine automatically activate the brake-control means which respond to the inertia cam while at the same time deactivating the brake-control means which respond to the diameter compensation cam.

The inertia cam undergoes gradual movement during paying out of the web from the pay-out roll and is S0 designed, that, in response to such movement, it gradually changes the adjustment of related brake-operating means proportionately to the changing inertia in the pay-out roll. lt follows that, when the winding machine is stopped, and the last-mentioned brake-operating means are automatically activated, said means: will establish a braking effect upon the pay-out roll such as to cause that roll to stop approximately apace to stopping of the take-up roll so that the tension of the intervening web will not become great enough to cause the web to break or become low enough to cause the web to continue paying out in a more or less uncontrolled fashion from the pay-out roll. During the mentioned stopping control exerted by the inertia cam, the mentioned dancer roll, and the brake controls responsive thereto, assist in maintaining the web at approximately a desired tension during the stopping of the machine.

The mentioned objects are accomplished by the present invention of which a single preferred embodiment is diagrammatically illustrated in the accompanying drawing without, however, limiting this invention to that precise embodiment.

In the drawing, 1t) is a pay-out roll from which a web W, indicated by dotted or broken lines, passes in the direction of an arrow applied thereto to a motordriven take-up roll (not shown).

The pay-out roll 10 is suitably mounted in the ma Chine and associated with its shaft (indicated by dot-andepesses...

3: dash line v11) isa brake 12, the braking effect of which `is increased by movement toward said brake (i.e., left# wardly as shown in the drawing) of a brake-operating rod 14.V Thewbrakingeffect is decreased by rightward lSllifting'ofsaidl brakeoperatingrod. The rod` 14 is:,in

the gnature of. a piston rod having rigidly connected thereto a piston 16 working in a double-acting cylinder 18'-havingpressure chambers 19 and 19a at? opposite ends4 thereof and the piston 16 in turn is rigidly connected by a-cor1nection rod 20 to a second piston 22 which .works in asingle-acting cylinder 24, having a pressure chamber 25 at one end and a chamber 25a, vented at 26 at its other end.

In passing from the roll 10 the web W passes about la-dancer roll 28, thence about a guide roll 30 whence it moves usually through suitable processing means to give the web whatever processing may be desired and thence theweb kmoves to the mentioned motor-driven take-up roll. The guide roll 30 is'a part of the machine which isron-a fixed axis therein while the dancer roll 28 is so mounted that-itmay move back and forth (horizontally as shown Vinthe drawing) and thereby actuate and control tension-compensating instrumentalities associated therewith.

The dancer roll 2S may be complemented in various ways-for control purposes, but for simplification it is described herein only inv one of many possible arrangements. The roll 28 is shown as supported against the effect of gravity as, for example, by having opposite, protruding vends of its shaft 32 slidably supported upon ixedhorizontal guide surfaces 34, only one of which is shown in the drawing. The dancer roll is yieldably held against the web W by air pressure, in a chamber 36 at one end of a pivotally mounted cylinder 38, acting upon a--piston 40 which is connected to opposite ends of the vdancer rolls shaft 32 by links 42 (one only being shown) connected between said shaft ends and, pivotally, to one arm or yoke of a bell-crank 44, the other arm of which is pivotally connected to the end of a piston rod. 46 flxedto the pistoni40. The cylinder 38 is pivotally supported on a bracket 4'7 and has a chamber 36a therein at the side of the piston 40 opposite from the chjamber 36, the chamber 36a being vented at 39.

At the pivotal point of the bell-crank 44 is arockshaft 48, mounted in a bracket 49 and constrained to `turnwith said bell-crank, said shaft having a cam S fixedthereon to turn therewith. Another somewhat `similar but oppositely acting cam 52 is linked to cam 50 by alink 54, thereby causing the two cams 50 and 52 lto work in unison in a manner and for purposes hereinafter described. Obviously, the cams 50 and 52 may kbothbe Xed to the' shaft 48 to turn therewith rather than be separately mounted and linked together as shown,

A follower assembly to cooperate, for control purposes, with the surface of a pay-out roll of diminishing diameter may be of various structural arrangements, one simple arrangement being shown as comprising a follower roller 56 mounted at the free end of an arm 5S having ati its other end a rock-shaft 60 mounted in a bracket 62. VThe roller 56 is' maintained in contact with the roll 10 Vby pressure in a chamber 64 in the lower end of a cylinder 66 which is pivotally mounted on a bracket 68, such pressure being effective upon a piston 70 in the cylinder 66 which piston has a piston rod 72 the end of which is pivoted to an intermediate point of the arm 58. The cylinder 66 has a second chamber therein, nurnbered 74, said chamber being vented at 76. Any piping or' tubing'l directly connected to cylinders 38 and 66 should be sufficiently exible to permit said cylinders to rock to some extent at their pivotal mountings.

Constrained to turn with theV rock-shaft 60 are two cams 78 and 80 one of which, the cam 78, may be fixed to the rock-shaft 60 and the cam 80 may be connected .tocam 78 by a link 82 constraining said two cams to work in unison in a manner and .for purposes hereinafter 4 described. Obviously, the cams 78 and 80 may both be fixed to the shaft'60'to turn therewith rather than be separately mounted and linked together as shown.

At this point it should be explained that, according to this invention, the cams 50 and 52, respectively, control the pressure in chambers19a and 19 of cylinder 18 while one or the other of cams 78 and S0, through hereinafter described selection means, .controls the pressure in cham ber 25 of cylinder 24. Such control of pressures by said four cams is achieved with .the cooperation of a uidpressure, system having pressure-regulating valves` 86, 92, 96, 100, 104, 108, and 112 therein such asare in common usage in various types of huid-pressure equipment, and therefore, are shown only diagrammatically. It should be understood that, within this invention, anvy valves may be employed which function in the manner described.

All of the previously mentioned pressure-regulating valves are fundamentallysimilar, but they are of..tw0 types: (1), plunger-operated and (2)v pressure-operated.

Valve 86 is plunger-operated. Formed within its casing are a vent chamber 200provided. with a vent port 201, a regulated-pressure chamber 2&2, and a line-pressure chamber 203. A Valve port 204 with a valve element 20S therein controls the passage of uid between chambers 202 and 203, the said valve element being normally held in its closed position in the port 204 by a compressed coil spring 206. l

A plunger or adjusting screwv207, threaded through the top of `the casingY of valve 36, is provided with. a knob or hand1e208 by means of which the screw can be turnedmanually to. cause it to move, longitudinally, inwardly or outwardly Vof thevalve casing. Compressed between the lower end of the screw and a centrally apen tured, central valving `disk 209 ofa ilexible diaphragm 210, is a compressedrcoil spring 211. The diaphragm 210 separates the chambers 200 and 262.

The valve element 205 has an integral, verticalextension, the upper end of which is formed as a` needle valve whichseats in the aperture of disk 209, the latter, and said..vertical extension, functioning` as a valve permitting controlled passage of pressurized uid from chamber 202 to V'chamber 200 in the operation of the device.

By manipulation of the yknob 20S, the screw 207 may be'turned down to increase the compression on spring 211 andthereby move valve element 205 downwardly to yopen port 204.1 This permits huid under pressure to pass from chamber 203 into chamber 202, and thence through pipe 88 into chamber 36 of the cylinder 38. WhenL the pressure inf chambers 36V and 202 builds up to a pressure corresponding to the setting of screw 207, thepressure in` chamber 202, acting upon the underside of diaphragm 210, opposes the force of spring 211, thereby enabling spring 206 to shift the valve element 205 to its closed position in port 204. li, through leakage or otherwise, there should be any loss of pressure in chamberv 36, the reduced pressure on the underside of diaphragm 210 enables spring Zll to' open valve4 element 205 relatively to port 204 sufficiently to bring about restoration of the desired pressure in said chamber. If it is desired to decrease the pressure in chamher'36 by manual control, the screw 207 is turned up or eased ofi, thereby reducing the compressive force of spring 211, which permits valving disk 209 to rise to cause the upper end of valve element 205to become unseated from within the aperture' in disk` 209, thereby permitting uid from chamber 292 to pass into chamber 200 and thence through port 201 to ambient atmosphere.

Valves 92', 1,00, 108, 110 are all plunger-operated.` As illustrated, they'are alike; and they differ from valve 86 only in that sliding plungers are substituted for; thc adjusting` screw 207 of valve 86. In operation, the plungers of theses everalvalves.controlthe'valves operation exactly asV screw 207 controls theoperationjof 4valve86. The;plungers ofvalvesr92, 100, 108 andg110 are actuated respectively by the cams 50, 52, 78 and 80, while, as already explained, adjusting screw 207 of valve 86 is manually actuated.

Valves 96, 104 and 112 are all pressure-operated and, as illustrated, are alike. They differ from the mentioned plunger-operated valves only in that iiuid pressure is employed therein to control them, instead of manual or mechanical operation. Referring to Valve 112 as illustrative of all the pressure-operated valves, fluid pressure, as elsewhere explained herein, is introduced through pipe 118 into the valve 112; more particularly, into a control pressure chamber 215 which is fluid-tightly separated from a vent chamber 216 by a diaphragm 217. The vent chamber 216 is provided with a vent port 218 freely communicating with ambient atmophere. A nonapertured disk 219, constituting a central part of the diaphragm 217, is rigidly interconnected with an apertured valving disk 220 of a diaphragm 221 (corresponding to diaphragm 210 of valve 86) by separated spacers 222 which permit fluid from beneath the diaphragm 221 to enter chamber 216 and vent through port 218.

It should be apparent that the principal diiference between the described plunger-operated valves and pressureoperated valves resides in the agencies by which they are controlled.

Air is mentioned herein as the fluid medium preferably employed in the disclosed tension-control apparatus although, within the invention, any suitable liquid or gas may be used as the :lluid medium.

A main pipe 84 is suitably connected to an air supply to maintain the air in said pipe at a pressure high enough to function in the manner described. From pipe 84, air is supplied to chamber 36 of cylinder 38 through a manually adjustable pressure-regulating valve 86 and a pipe 88, said valve being desirable to permit the maintenance l of such closely controlled pressure in chamber 36 as will substantially balance the desired tension in the web W;

this balance being effective through the bell-crank 44.

A pressure gauge 90 may be provided in pipe 88 to indicate such maintained pressure.

Air from pipe 84 is supplied directly to chamber 64 of cylinder 66 to cause piston 70, through rod 72, to hold follower roller 56 continuously in engagement with the surface of roll 10.

Control of the pressure in chambers 19a and 19 by cams 50 and 52 is achieved through simiiar valve arrangements. The cam surface of cam 50 operates a plunger of a plunger-operated pressure-regulating valve 92 to .cause the latter to pass air from pipe 84, by way of pipe 94 at a regulated pressure to a relay valve 96. The valve 96 is a pressure-regulating valve which, in response to the regulated pressure delivered to it by pipe 94, passes air from pipe 84 to pipe 93 and, thence, at a regulated pressure to chamber 19a. The cam surface of cam 52 operates through a similar valve and pipe arrangement to regulate the delivery of air to chamber 19, said arrangement comprising a plunger-operated pressure-regulating valve 100, a pipe 102 from the latter valve to a relay valve 104 which passes air from pipe 84 to a pipe 106 and, thence, at a regulated pressure to chamber 19.

It should be understood that as cam 50 pushes the plunger of valve 92 down, cam 52 permits the plunger of valve 100 to rise, and vice versa. Thus, if the tension in web W increases beyond the tension desired therein, the web pulls dancer roll 2S rightwardly to cause the bell-crank 44 to turn clockwisely. Cam 50, turning similarly with the bell-crank permits the plunger of valve 92 to rise thereby reducing the pressure in pipe 94 and in the upper chamber in valve 96 and causing` the latter valve to reduce the pressure communicated therethrough and by way of pipe 98 to chamber 19a, permitting piston 16 to shift slightly rightwardly to slightly ease off the effect of brake 12 and thereby cause the desired decrease i in the tension in the web W to bring that tension to its desired value.

The just-described tension decrease, however, is effected not only through the mentioned decrease of pressure in chamber 19a but through a simultaneous increase of pressure in chamber 19, causing instantaneous shifting of the piston 16 and operation of brake 12 to yield instantaneous correction of the web tension rather than a more or less sluggish correction which would occur if pressure variations were not effective simultaneously upon both sides of the piston 16. The mentioned simultaneous increase of pressure in chamber 19 results from operation of cam 52, functioning oppositely in unison with cam 50 in the presence of increased web tension.

lt will be understood that, to compensate for an undesired decrease in the tension of web W, the cams 50 and 52 will turn counterclockwisely causing valves 92 and 96 to increase the pressure in chamber 19a and cause valves 100 and 104 to decrease the pressure in chamber 19, thereby instantaneously increasing the braking effect to restore the desired tension in the web.

Control of the pressure in chamber 25 by one or the other of cams 78 and 80 is achieved through plural valve arrangements either of which may be selectively brought into operation, such selection depending on whether tension control is to be based upon the diminishing diameter of the pay-out roll 10 or the diminishing intertia force in said pay-out roll.

The just-mentioned valve arrangements comprise similar plunger-controlled pressure-regulating valves 108 and 110, the plunger of valve 108 being arranged to be operated by cam '78 which will sometimes hereinafter be referred to as an inertia compensating cam and the plunger of Valve 110 being arranged to be operated by cam 80 which will sometimes hereinafter be referred to as the diameter compensating cam. Compressed air is supplied to both valves 108 and 110 directly by main pipe 84.

One or the other of valves 108, 110 is selectively connected to a relay valve 112 by a solenoid operated valve 114 which, in the condition thereof shown in full lines in the drawing, establishes air connection of valve 110 to valve 112 through pipes 116 and 118. When solenoid 114a of valve 114 is energized upon stopping of the winding machine, in the manner hereinafter more fully explained, said solenoid operates the valve 114 so that the valve element thereof will turn or shift to its condition shown in broken lines in the drawing to break air communication between valves 11i? and 112 and to establish air communication from valve 108 to valve 112 through pipes and 110. The Valve 114 is so designed that its casing or some other part of said Valve will constitute a block, indicated at 114b, so arranged as: to block off passage of air from whichever of valves 108, 110 is not connected through valve 114 to valve 112. The pressure of air in the upper chamber of valve 112 controls the latter to control or regulate the pressure of air which said valve may pass from pipe 84 through pipe 122 to chamber 25 of the cylinder 24.

The showing of the cam surfaces of cams 78 and 80 in the drawing should not be taken to be exact. In actual practice those cam surfaces may, except on close scrutiny, appear to be substantially alike. However, the surface of cam 80 will be shaped to cause such operation of valve 110 as will compensate for the changing effect on roll 10 of the pull exerted by the web on said roll because of the gradually diminishing diameter of that roll; while the cam surface of cam '78 is shaped to exert such control on valve 108 as will compensate for the gradual diminishing of inertia of roll 10 as the web is payed out from that roll.

Although the foregoing should afford a fairly complete understanding of the operation of the disclosed apparatus, the following summary of operation of the apparatus should be helpful. When a Winding machine including apparatus according to this invention is ready to commence a winding operation, the web is as indicated in ibrolen lines in the -drawing and theva'riou's parts' of the apparatus are in their conditions as indicated in full lines in the drawing. Complete winding apparatus includes a motor (not shown) to operate a take-up roll (also not shown) for the purpose of pulling the web W from pay-out roll 10. An electric switch 124 for controlling solenoid 114a and shown merely as a normally open switch, may be a normally open contactor of a relay in the electrical equipment by means of which the machine is operated; and said switch is normally open as `shown in the drawing during normal running of the machine. In that situation solenoid 11411 is in a deenergized condition and Valve 110 is connected to valve 112 through valve 114 while passage of air through valve 108 is prevented by reason of the fact that pipe 120 is closed off at 114b.

In the just-described condition, the cams 50, 52 working oppositely but in unison during running of the web W from roll 10, serve to maintain very rapid compensation for tension variations in the web as reected by shiftving or vibrating of the dancer roll 2S, such compensation being achieved through the operation by said cams of plunger valves 92 and 100 controlling relay valves 96 and 104 which in turn control the delivery of air under pressure to chambers 19a and 19 to cause practically instantaneous operation of brake 12 and thereby cause practically instantaneous compensation for tension variations in the running web.

In addition to the described tension control resulting from coaction of the dancer roll 2S with cams 50 and 52 and valves controlled by the latter cams, piston 22, during running of the machine, is acted upon by compressed air controlled by cam 80 and valves 110, 114 and 112. As the diameter of roll diminishes, cam 80 pushes the plunger of valve 110 inwardly thereby reducing the pressure of air passing through that valve to valve 112. In turn, the reduced pressure of air delivered to the upper chamber of valve 112 reduces the pressure of air which the latter valve may deliver to chamber 25 so that, insofar as piston 22 is concerned, the braking force applied 'at roll 10 through brake 12 is diminished as the diameter of roll 10 diminishes. In the way described, the torque on roll 10 exerted by the pull on the web W is kept quite uniform throughout the entire unwinding of the web from said roll.

When the machine is suddenly stopped, such substantially uniform torque conditions become suddenly interrupted by the inertia of the turning roll 10 which upsets tension conditions in the web W unless additional tension compensation is provided. To achieve such additional tension compensation according to this invention, the switch or contacter 124 automatically closes when the machines electrical stopping controls (not shown) are operated thereby energizing solenoid 11461 to cause the valve element of valve 114 to shift from its full line to its broken line position shown in the drawing, in which shifted position the tension-controlling effects on cam 80 and valve 110 are discontinued because of pipe 116 being blocked off at 1Mb. At the same time, the valve 114 establishes communication from valve 10S to valve 112 by way of pipes 120 and 118 thereby causing relay valve 112 to pass air from pipe 84 through pipe 122 to chamber 25 so that the pressure exerted upon piston 22 is then established with reference to the inertia in the unspent portion of roll 10.

The cam surface of cam 78 is shaped so that, even though valve 108 is inactive during normal running of the machine, its adjustment is continuously undergoing alteration corresponding to the gradually diminishing diameter and weight of the roll 10 as web is payed out therefrom. As the reduction of said rolls Weight brings about a corresponding change in the inertia condition of said roll, it follows that the mentioned adjustment of cam 78 continuously undergoes alteration corresponding 'to the changing ofthe inertia condition in said roll.

Thus, 'during stoppin'gof the machine; ethevalvs 108 and 112 cooperate to establish the proper pressu chamber 25 to enable the piston 22 to set upsuch compensatory operation ofbrake 12 that the tension of web W is compensated in direct relation to such inertia. It should be realized that, during stopping of themachine, any tension changes in the web W are also reilected in the action of the dancer roll 23 so that the cams 50 and 52 cooperate with cam 78 in properly con trolling the tension of the web at that time. If desired, pressure gauges 130, 132, 134 and 136 may be provided for the convenience of those operating the machine.

Although the valve combinations shown in the draw'-l ving are considered preferable, the present inventive concept does not require the use of relay valves 96, 104 or 112. if such valves were omitted, valves 92, and 108 or 110 would directly pass air, respectively, to chambers 19a, 19, and 25.

Also, in a winding machine designed for use under certain limited conditions, asingle cam and related fluid. circuit may be substituted for the two cams 78 and 80 and the two fluid circuits controlled thereby. In such an arrangement, the single cams surface would -be shaped to correspond substantially to the diminution of thein ertia in the pay-out roll 10, during running of the inachine; and, to some extent, that shape would afford some compensation for the diminishing diameter of said roll.. In such an alternative arrangement, no selection meanssuch as valve 114 would be needed.

It should be obvious that the disclosed inventive 'con-- cepts may be embodied in various structures and arrange-Y -ments other than those shown `and described herein, Without departing from the invention as set forth in the -fol lowing claims.

`I claim:

l. Web-tension-controlling apparatus comprising a brake adapted to oppose rotation of a pay-outiroll'of a winding machine to oppose withdrawal of a web from said'r-oll, tension-sensing means adapted to reciprocate in response to variations in tension of such a web during such withdrawal, cam meansy having oppositely effective cam surfaces coacting with said tension-sensing means to derive movement from the latter substantially proportional to reciprocation of said tension-sensing means, brake-operating means coacting with said brake to in crease and decrease the braking effect of the latter, Va pair of fluid-pressure chambers coacting oppositely lwith said brake-operating means to actuate the latter, and a pair of Huid-pressure valves coacting with and under the control of said cam surfaces to communicate fluid pressure separately to said chambers to vary the 'Huid-pressures in the latter inversely in response to variations in the tension of the web.

2. Apparatus according to claim l, said tension-sensing means comprising a dancer roll and a lever coacting with said dancer roll and with said cam means to operate the latter.

3. Apparatus according to claim 1, further including fluid-pressure means coacting with said tension-sensing means to maintain the latter in tension-sensing relation to such a web.

4. Apparatus according to claim 1, said cam lsurfaces being adapted to work in unison.

5. Web-tension-controlling apparatus comprising braking means adapted to oppose rotation of a pay-out roll of a winding machine to oppose withdrawal of a web from said roll, tension-sensing means adapted to vreciprocate in response to variations in tension of such a web during such withdrawal, inertia-sensing means adapted to move with the diminution of the inertia in said roll as web is payed out therefrom, and separate brake-operating means coacting separately with said tension-sensing means and said inertia-sensing means to compensate '-for tension variations in the web during runniiigfof saidiii'achine and to exert a stopping-braking etect upon said roll upon stopping of the machine.

6. Wel:tensioncontrollinfy apparatus comprising a brake adapted to oppose rotation of a pay-out roll of a winding machine to oppose movement of a web from said roll, tension-sensing means adapted to reciprocate in response to variations of tension of such a web during such movement of the web from the roll, rst brake-operating means variably operable in response to the reciprocation of said tension-sensing means and coacting with said brake to cause the latter to vary the braking effect of said brake to compensate for such tension variations, diameter-sensing means adapted to move in response to diminution of the diameter of the pay-out roll, a cam surface movable in response to such movement of said diameter-sensing means and being shaped to correspond substantially with the reduction in the inertia of said roll as the diameter of the latter diminishes, and second brakeoperating means coacting with said cam surface and with said brake to cause the latter to exert a diminishing braking force substantially proportional to the diminishing inertia in the pay-out roll; said first brake-operating means being adapted to operate said brake to compensate substantially for web tension conditions arising from the braking force exerted by said brake as a result of operation of said second brake-operating means during running of the machine.

7. Apparatus according to claim 6, said second brakeoperating means comprising fluid-actuated means for operating said brake and a duid-pressure-regulating valve, controlled by said cam surface, and adapted to control the communication of fluid pressure to said fluid-actuated means.

8. Web-tension-controlling apparatus comprising braking means adapted to oppose rotation of a pay-out roll of a winding machine to oppose withdrawal of a web from said roll, tension-sensing means adapted to reciprocate in response to variations in tension of such a web during such withdrawal, diameter-sensing means adapted to move in response to diminution of the diameter of the payout roll, iirst brake-operating means responsive to reciprocation of said tension-sensing means and coacting with said braking means to cause the latter to vary the braking eect of said braking means to compensate for such tension variations, second brake-operating means responsive to the movement of said diameter-sensing means and coacting with said braking means to cause the latter to vary the braking effect of said braking means to compensate for the variance in the effect of the pull of the web on said roll as the latters diameter diminishes,

third brake-operating means for operating said braking means, said third brake-operating means being responsive to the movement of said diarzieter-sensing means to maintain such adjustment of said third brake-operating means as to keep the latter, continuously in condition, during running of the machine, to compensate for the variance in the inertia of the pay-out roll as the latters diameter diminishes, and selection means, operative upon initiation of an operation for stopping the winding machine, for deactivating said second brake-operating means and activating said third brake-operating means.

9. Apparatus according to claim 8, said diameter-sensing means comprising a follower, maintained in contact with the surface of the pay-out roll during running of the winding machine.

10. Apparatus according to claim 8, said second brakeoperating means comprising a first cam surface shaped to conform substantially to the variance in the diameter of the pay-out roll during the running of the winding machine and coacting with said braking means to operate the latter, and Said third brake-operating means comprising a second cam surface shaped to conform substantially to the variance in the inertia of the pay-out roll during the running of the winding machine and coacting with said braking means to operate the latter.

11. Apparatus according to claim l0, said two cam surfaces being constrained to move in unison in response to movement of said diameter-sensing means.

12. Apparatus according to claim 10, said second and third brake-operating means comprising separate fluidpressure means, each of the latter including a pressureregulating valve, for separately operating said braking means, said valves coacting separately with said two cam surfaces to derive operation therefrom.

13. Apparatus according to claim 8, said second and third brake-operating means being fluid-pressure means, and said selection means comprising a solenoid-operated valve.

14. Apparatus according to claim 8, said second and third brake-operating means being fluid-pressure means, and said selection means comprising a solenoid-operated valve, and said valves solenoid being connected as a part of means for stopping the winding machine and adapted to operate automatically, when said stopping means are operated, to deactivate said second brake-operating means and to activate said third brake-operating means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,343,181 Heinz Feb. 29, 1944 

